The present disclosure relates to measuring the phase transition pressure of a downhole fluid extracted from a subterranean formation into which a well has been drilled.
It is conventional to investigate the characteristics of downhole fluids contained in underground formations by taking samples and analyzing the samples in a laboratory or in situ. In particular, a downhole fluid characteristic is the phase transition pressure, which may be one of a bubble point pressure, a dew point pressure, or an asphaltene onset pressure.
Some methods and apparatuses may utilize pressure versus volume curves to determine a phase transition pressure. Disclosures of such methods or apparatuses may be found, for example, in U.S. Pat. Nos. 4,782,695; 5,329,811; 5,473,939; 5,635,631; 6,334,489; 7,346,460; and 7,461,547, and U.S. Patent Application publication No. 2009/0078036, the disclosures of which are incorporated herein by reference.
Methods and apparatuses may also utilize variations of a fluid property as a function of pressure to determine a phase transition pressure. Disclosures of such methods or apparatuses may be found, for example, in U.S. Pat. Nos. 5,167,149; 5,741,962; 6,128,949; 6,223,588; 6,501,072; 6,758,090; 6,792,798; 7,002,142 and 7,075,063, the disclosures of which are incorporated herein by reference.